John d



".PETERS PHOTO-LITHOGRAPHER. WASNINGYON D C @eine faire gatnt @ffice Letters Patent No. 80,677, dated August 4, 1868.

IMPROVEMENT IN BauNetz-SLIDE VALVES.

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TO ALL WHOM IT MAY CONCERN:

Be it kno-wu that I, JOHN D STEWAR'LQOF La Porte,lin the county of La Porte, and State of Indiana, haveinvented a new and useful Improvement in Slide-Valves for Steam-Engines; and I do hereby declare that the following is a full, clear, andexact description of the same, reference being had to the annexed drawings, making part of this specification, in which- Figure 1 is a perspective view of the valve-chest.

Figure 2 is a vertical-longitudinal section of the valve and chest.

Figure 3 is a section of the same, on the linea: x, fig. 2, showing the top of valve-ehest ou one side, and the plate on the other side. I l

The same letters are employed in all the'gures for the indication of the same parts.

My improvement consists in the construction and arrangement ofthe valve and chest, and in the combination with the same of packing-plates, held in-contaet with the valve by thepressure of the-steam on the top of said plates. Y v

In the annexed drawings.-

A is the valve-stem, to which a reciprocating motion is communicated in the ordinary manner.

B is a slide-valve, actuated by the valve-stem. vvItis. a. metallic rectangular block, fitting neatly in the chamber of the valve-chest, and sliding on'the bottom thereof. It is constructed with two vertical slots BI through the lap ofthe valgve, through which the steam passes to the induction-ports C C, and with a cbamberecl recess, B2, forming, with-the movemfent offthc valve, a communication for the passage of the' steam alternately from the ports C C to the eduction-port D.

The steam is admitted from the steam-pipe atE into a steam-chamber, F, on the top of the valve-chest, from which it passes Valternatelywith the movement o't'.the valve, through` openings F F', into the passages B B through the valve into the induction-ports C G. I y

Tivo plates, H I-I, areA placed in the top of the chamber of the valve-chest G, being received in recesses formed for the purpose in the top of the chest G. -These plates are pressed by steam entering from the open ings F into longitudinal grooves,- shown at GZ, iig. 3, upon the topof the valve B. These .platesare for the purpose of `relieving the valve from the friction which would be caused by having them lit tightly into the valvechest,.and bythe pressure of the full force of the steam ou the back of the valve, and to permit the expansion and contraction of the valve, while, at the same time, preventingthe passage of the steam over the top of the valve from one openingfB to the other. 'An equivalent arrangement would be to substitute for the longitudinal grooves Gr2 a series of holes openingfrom the steam-chamber F through the cover Gl, admitting the pressure ofrtlle steam to the top of the plates H. The upper and lower faces of the valve should be ground to make steam-tight surfaces.

What I claim as my invention, and desire to secure by Letters Patent, is-

In combination with the slide-valve B, valve-chest G, and cover G1, ads'tearm-chamber F, the packingplates H, to the back of which steam is admitted 'from the steam-chamber,'substantially as and for the purpose set forth. l i

In testimony whereof, I have signed my name to this specification in the presence of two subscribingwitnessesr JOHN D. STEWART.

Witnesses:

E'. L. BENNET, .JOHN H. ORcAN. 

